One dead and four missing as Japanese landslide engulfs road repair crew.

A repair crew working on a damaged mountain road above the city of Yurihonjo in Akita Prefecture, Japan, were swallowed by a huge landslide when the road collapsed completely at about 3.20 pm local time (6.20 am GMT) on Thursday 21 November 2013. The body of one of the workers was later recovered, with four still missing at the time of writing. 

The site of the 21 November 2013 Yurihonjo landslide. Kyodo News.

The road had been closed for some months after cracks appeared, and quantity of heavy machinery had been brought to the site before the collapse, suggesting that the repairs triggered a landslide on an existing week point in the underlying rock. There was snow at the site, which would imply sub-zero temperatures, which can also be a factor in triggering landslides, as water in cracks in rock expands as it freezes, forcing the cracks further apart.

The approximate location of the 21 November 2013 Yurihonjo Landslide. Google Maps.

See also At least 17 dead as Typhoon Wipha hits Japan, Couple, baby, rescued after Philippine landslide, At least six dead following landslide on Luzon Island, the Philippines, One person confirmed dead and two more missing as Typhoon Man-yi hits Japan and Man killed by rockfall on Luzon Island, the Philippines.

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Magnitude 4.9 Earthquake in southeast Croatia.

The United States Geological Survey recorded a Magnitude 4.9 Earthquake at a depth of 10 km, roughly 7 km east of the town of Otok in southeast Croatia, slightly before 9.00 am local time (slightly before 8.00 am GMT) on Monday 18 November 2013. There are no reports of any damage or casualties arising from this quake, though it was felt over a fairly wide area.

The approximate location of the 18 November 2013 Otok Earthquake. Google Maps.

The coastal region of Croatia, and the other states of the western Balkan Peninsula, forms the eastern margin of the Adriatic Plate, a piece of the African Plate that has broken away and is now wedged into the southern part of the Eurasian Plate. This is being squeezed by the impact of Africa into Europe from the south, which is pushing western Italy, which sits on the Eurasian Plate, to the east, and Greece and Turkey, which sit on the Aegean and Anatolian Plates, to the west. This squeezing leads to uplift around the margins of the Adriatic Plate, in the Apennine Mountains of central Italy and the mountain ranges of the west Balkan Peninsula.

See also Magnitude 3.1 Earthquake in northern Macedonia, Eruption on Mount Etna, Magnitude 4.2 Earthquake in eastern Austria, Magnitude 4.6 Earthquake in western Romania and Magnitude 4.5 Earthquake off the Adriatic Coast of Italy.

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The origin of the Chelyabinsk Meteor.

On 15 February 2013 at about 9.20 am Yekaterinburg Time (about 3.20 am GMT), a large object entered the Earth's atmosphere over southern Russia at about 67 000 km per hour (almost 60 times the speed of sound) exploding over the province of Chelyabinsk at an altitude of about 23.3 km, generating a shock wave that shattered buildings in six cities, leading to about 1500 people being injured (this is the first ever recorded event in which people have been injured by a meteorite). It is estimated that the object was between 17 and 20 m in diameter and 12 000-13 000 kg in mass, though only about 650 kg of fragmentary material was recovered on the ground despite an extensive search, suggesting that less than 1000 kg reached the Earth's surface.

The trail of the Chelyabinsk Meteor, taken 2-3 minutes after it exploded. T.T. Uragan/Wikimedia Commons.

In a paper published on the online arXiv database at Cornell University Library on 10 August 2013, and submitted to the Monthly Notices of the Royal Astronomical Society, Carlos and Raúl de la Fuente Marcos of the Universidad Complutense de Madrid attempt to calculate the trajectory of the object prior to its encounter with the Earth, in order to determine its origins.

De la Fuente Marcos & de la Fuente Marcos calculate that the Chelyabinsk meteor shared a common origin with the Apollo Group Asteroid 2011 EO40, around 20-40 000 years ago. They also suggest that several other known asteroids, 2007 BD7, 2008 FH and 2010 DU1 as well as a number of smaller objects, may be part of the same family, which they describe as the Chelyabinsk Asteroid Family, although they not that these objects have perturbed orbits due to frequent encounters with Venus, the Earth-Moon System, Mars and Ceres.

The orbit of 2011 EO40. JPL Small Body Database Browser.

De la Fuente Marcos & de la Fuente Marcos suggest that to be considered a member of the Chelyabinsk Asteroid Family an asteroid should have a semi major access (average distance from the Sun) of 1.66  ± 0.08 au (i.e. 1.66 times the distance between the Earth and the Sun, give or take 0.08 times the distance between the Earth and the Sun), an eccentricity of 0.54 ± 0.02 (on a scale where 0 is a circular orbit and 1 a parabolic path that escapes from orbit) and an inclination of 3.7 ± 1.3° to the plane of the Solar System.

The orbit of 2007 BD7. JPL Small Body Database Browser.

See also The Eulalia and Polana asteroid families, The nature and history of 'Quasi-Hilda Object' 2000 YN30, The dust tail of 3200 Phaethon, Four more asteroids found to be co-orbitals of Neptune and 2012 LZ1; bigger than we thought.

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25 miners believed to be dead after explosion at gold mine in Guinea Conakry.

Fourteen miners are known to have died following an explosion at a gold mine in the Siguiri region of northeaster Guinea Conakry on the evening of Tuesday 19 November 2013, and it is believed that around twenty five have lost their lives in total. The mine fell within the area of a concession granted to the Ashanti Goldfields Corporation, but is understood to have been operated artisanally (informal, unregulated mining seldom featuring any form of heath and safety procedures). 

The approximate location of the Siguiri gold mine. Google Maps.

Gas explosions typically occur in mines when miners hit pockets of methane (CH₄), a highly flammable gas that is given off by coal under pressure. Typically when a seam containing pressurized gas is cut into it bursts, releasing the pressure and throwing large blocks of coal into the faces of the miners, often with fatal results. Thus although the gas involved is flammable it does not actually need to ignite to cause fatalities. In this instance the explosion appears to have resulted in the collapse of a number of shafts between 20 and 25 m bellow the surface.

Guinea is considered to have some of the largest gold reserves in Africa, as well as large reserves of bauxite (aluminium ore), iron and diamonds, but poor infrastructure and political instability has led to little outside investment in the country until fairly recently. The country is extremely underdeveloped and most of its population is extremely poor. This leads to a situation whereby artisanal mining, while technically illegal, is tolerated by the authorities, often leading to complaints of weak property laws by foreign companies operating in the country.

See also Human Rights Watch reports on child labour in the Tanzanian gold mining industry, Amnesty International reports on the mining industry in Katanga Province, Democratic Republic of Congo, At least 20 miners killed in North Kivu mine collapse, Over 60 feared dead in Darfur gold mine collapse and Two Sierra Leonean artisanal miners killed by soil cave-in.

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Woman killed in Kenya landslide.

A woman has been killed and several families have been displaced after a landslide swept through Mugomet Village in Elgeyo-Marakwet County, Kenya, on Wednesday 20 November 2013. She as been named Mary Kigen (50), who was swept away when the house was was partially destroyed by the incident. A number other people in the house, including several children, were unharmed, as were the occupants of two other houses which were completely destroyed by the landslip. A grain store was also destroyed, as were sections of several roads. In addition to the people who lost their homes, several neighbouring families were evacuated to safer ground as a precaution.

The approximate location of the 20 November 2013 Mugomet landslide. Google Maps.

The incident occurred after about a month of heavy rains, in one of the area's two annual rainy seasons. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. This two rainy seasons per year pattern is typical in equatorial countries, with rainy seasons around the equinoxes and dry seasons around the solstices. Upland areas of Kenya have always been prone to landslides, but the problem has become worse in recent years as a rising population has led to more agriculture on hillslopes, in many areas replacing open woodland where tree roots served to stabilize slopes, and also to more people living in harms ways. Villagers in Mugomet had been petitioning the government to be relocated to a safer area for some time prior to this latest incident.

See also Four killed by landslide in Katsina State, northern Nigeria, Landslide at limestone quarry kills six in Omdurman, Sudan, At least fifteen dead following landslide in Freetown, Sierra Leone, Four year old boy killed by landslide in Bududa District, eastern Uganda and Three children killed by landslip in Kenya.

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Asteroid 2013 VO4 passes the Earth.

Asteroid 2013 VO4 passed the Earth at a distance of 4 313 000 km (11.23 times the distance between the Earth and the Moon), slightly after 6.30 am on Tuesday 12 November 2013. There was no danger of the asteroid hitting us, and even were this not the case it would have presented little danger to us. 2013 VO4 is estimated to be between 7 and 23 m in diameter, and an object of this size would be expected to break up in the atmosphere between 37 and 18 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2013 VO4. JPL Small Body Database Browser.

2013 VO4 was discovered on 4 November 2013 by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2013 VD17 implies that the asteroid was the 114th object discovered in the first half  of November 2013 (period 2013 V).

2013 VO4 has a 710 day orbital period and an eliptical orbit that takes it from slightly under 1.00 AU from the Sun (i.e. slightly closer to the Sun than the Earth) to 2.11 AU from the Sun (i.e. 211% of the average distance at which the Earth orbits the Sun, outside the orbit of Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer).

See also Asteroid 1997 WQ23 passes the Earth, Asteroid 2013 VD17 discovered after passing the Earth, Asteroid 6063 Jason (1984 KB) passes the Earth, Asteroid 138852 (2000 WN10) passes the Earth and Asteroid 2013 VN5 passes the Earth - then gets discovered.

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Volcano creates new island in the west Pacific.

A volcano has created a new island off the shore of Nishinoshima, a remote and uninhabited island Belonging to Japan, which is about 1000 km south of Tokyo and about 1600 km north of Guam. The island is about 200 m in diameter. It is unclear exactly when the island first appeared, but on Wednesday 20 November 2013 the Japan Coast Guard issued a warning about smoke and ash issuing from the new island (aircraft need to avoid volcanic ash as it melts in their engines, forming a glassy substance), and TV footage of an eruption on the island has subsequently emerged.

Steam issuing from the new volcanic island on Wednesday 21 November 2013. Japan Coast Guard.

Nishinishima lies on he boundary between the Pacific and Philippine Plates, where the Pacific Plate is passing beneath the Philippine Plate as it is subducted into the Earth. As the Pacific Plate is subducted it is melted by the heat and pressure of the planet's interior. The lighter fractions of this melted material then rise through the overlying Philippine  Plate as magma, fueling the volcanoes of the various islands and island groups that lie along the boundary.

The approximate location of the new island. Google Maps.

While the island can accurately be described as new, it is not evidence of a new volcano, rather a new vent on the side of the main Nishinishima volcano. It is unlikely to remain as a new island. Most probably the bulk of the material is poorly consolidated ash and cinders, which will be quickly eroded away. If the vent does start to produce more permanent rock-forming lava then this will be more resilient to erosion, but in this case the island is likely to grow and become attached to the Nishinishima mainland.

See also Tokyo shaken by Magnitude 5.4 Earthquake on the Bōsō Peninsula, Magnitude 6.8 Earthquake off the east coast of Japan, Eruption and pyroclastic flow on Sakurajima, Kyushu, Magnitude 5.8 Earthquake in Fukushima Prefecture, Japan and Magnitude 6.9 Earthquake in the Izu Islands to the south of Japan.

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